/* See COPYRIGHT for copyright information. */

#include <inc/x86.h>
#include <inc/error.h>
#include <inc/string.h>
#include <inc/assert.h>

#include <kern/env.h>
#include <kern/pmap.h>
#include <kern/trap.h>
#include <kern/syscall.h>
#include <kern/console.h>
#include <kern/sched.h>

// Print a string to the system console.
// The string is exactly 'len' characters long.
// Destroys the environment on memory errors.
static void
sys_cputs(const char *s, size_t len)
{
	// Check that the user has permission to read memory [s, s+len).
	// Destroy the environment if not.
	
	// LAB 3: Your code here.
    user_mem_assert(curenv , (void*)s , len , PTE_U|PTE_P|PTE_W);
	// Print the string supplied by the user.
	cprintf("%.*s", len, s);
}

// Read a character from the system console without blocking.
// Returns the character, or 0 if there is no input waiting.
static int
sys_cgetc(void)
{
	return cons_getc();
}

// Returns the current environment's envid.
static envid_t
sys_getenvid(void)
{
	return curenv->env_id;
}

// Destroy a given environment (possibly the currently running environment).
//
// Returns 0 on success, < 0 on error.  Errors are:
//	-E_BAD_ENV if environment envid doesn't currently exist,
//		or the caller doesn't have permission to change envid.
static int
sys_env_destroy(envid_t envid)
{
	int r;
	struct Env *e;

	if ((r = envid2env(envid, &e, 1)) < 0)
		return r;
	env_destroy(e);
	return 0;
}

// Deschedule current environment and pick a different one to run.
static void
sys_yield(void)
{
	sched_yield();
}

// Allocate a new environment.
// Returns envid of new environment, or < 0 on error.  Errors are:
//	-E_NO_FREE_ENV if no free environment is available.
//	-E_NO_MEM on memory exhaustion.
static envid_t
sys_exofork(void)
{
	// Create the new environment with env_alloc(), from kern/env.c.
	// It should be left as env_alloc created it, except that
	// status is set to ENV_NOT_RUNNABLE, and the register set is copied
	// from the current environment -- but tweaked so sys_exofork
	// will appear to return 0.

	// LAB 4: Your code here.
    struct Env * newenv;
    int a = env_alloc(&newenv, curenv->env_id);
    if(a < 0)
        return a;
    newenv->env_tf = curenv->env_tf;
    newenv->env_status = ENV_NOT_RUNNABLE;
    newenv->env_tf.tf_regs.reg_eax = 0;
    return newenv->env_id;
	//panic("sys_exofork not implemented");
}

// Set envid's env_status to status, which must be ENV_RUNNABLE
// or ENV_NOT_RUNNABLE.
//
// Returns 0 on success, < 0 on error.  Errors are:
//	-E_BAD_ENV if environment envid doesn't currently exist,
//		or the caller doesn't have permission to change envid.
//	-E_INVAL if status is not a valid status for an environment.
static int
sys_env_set_status(envid_t envid, int status)
{
	// Hint: Use the 'envid2env' function from kern/env.c to translate an
	// envid to a struct Env.
	// You should set envid2env's third argument to 1, which will
	// check whether the current environment has permission to set
	// envid's status.
    if(status != ENV_RUNNABLE && status != ENV_NOT_RUNNABLE)
        return -E_INVAL;
    struct Env * setenv;
    envid2env(envid, &setenv, 1);
    if(setenv == NULL)
        return -E_BAD_ENV;
    setenv->env_status = status;
    return 0;
	// LAB 4: Your code here.
//	panic("sys_env_set_status not implemented");
}

// Set envid's trap frame to 'tf'.
// tf is modified to make sure that user environments always run at code
// protection level 3 (CPL 3) with interrupts enabled.
//
// Returns 0 on success, < 0 on error.  Errors are:
//	-E_BAD_ENV if environment envid doesn't currently exist,
//		or the caller doesn't have permission to change envid.
static int
sys_env_set_trapframe(envid_t envid, struct Trapframe *tf)
{
	// LAB 5: Your code here.
	// Remember to check whether the user has supplied us with a good
	// address!
	//panic("sys_env_set_trapframe not implemented");
    struct Env *e;
	int r;
	if((r = envid2env(envid, &e, 0)) < 0){
		return r;
	}
    /* if((vpd[VPD(tf)] & PTE_P) == 0 || */
    /*    (vpt[VPN(tf)] & PTE_P) == 0 || */
    /*    (vpt[VPN(tf)] & PTE_U) == 0){ */
    /*     return -E_INVAL; */
    /* } */
    user_mem_assert(e, (void*)tf, sizeof(struct Trapframe), PTE_P);
    e->env_tf = *tf;
    e->env_tf.tf_eflags |= FL_IF;
	return 0;	
}

// Set the page fault upcall for 'envid' by modifying the corresponding struct
// Env's 'env_pgfault_upcall' field.  When 'envid' causes a page fault, the
// kernel will push a fault record onto the exception stack, then branch to
// 'func'.
//
// Returns 0 on success, < 0 on error.  Errors are:
//	-E_BAD_ENV if environment envid doesn't currently exist,
//		or the caller doesn't have permission to change envid.
static int
sys_env_set_pgfault_upcall(envid_t envid, void *func)
{
	// LAB 4: Your code here.
    struct Env * env;
    if(envid2env(envid, &env, 1) < 0)
    {
        return -E_BAD_ENV;
    }
    // pte_t *entry = pgdir_walk(curenv->env_pgdir, (void *)env, 1);
    //if((entry != NULL) && (*entry & PTE_U) && (*entry & PTE_W))
        // {
    env->env_pgfault_upcall = func;
    return 0;
        // }
        //return -E_BAD_ENV;
	//panic("sys_env_set_pgfault_upcall not implemented");
}

// Allocate a page of memory and map it at 'va' with permission
// 'perm' in the address space of 'envid'.
// The page's contents are set to 0.
// If a page is already mapped at 'va', that page is unmapped as a
// side effect.
//
// perm -- PTE_U | PTE_P must be set, PTE_AVAIL | PTE_W may or may not be set,
//         but no other bits may be set.  See PTE_USER in inc/mmu.h.
//
// Return 0 on success, < 0 on error.  Errors are:
//	-E_BAD_ENV if environment envid doesn't currently exist,
//		or the caller doesn't have permission to change envid.
//	-E_INVAL if va >= UTOP, or va is not page-aligned.
//	-E_INVAL if perm is inappropriate (see above).
//	-E_NO_MEM if there's no memory to allocate the new page,
//		or to allocate any necessary page tables.
static int
sys_page_alloc(envid_t envid, void *va, int perm)
{
	// Hint: This function is a wrapper around page_alloc() and
	//   page_insert() from kern/pmap.c.
	//   Most of the new code you write should be to check the
	//   parameters for correctness.
	//   If page_insert() fails, remember to free the page you
	//   allocated!

	// LAB 4: Your code here.
    if(((perm | PTE_USER) != PTE_USER) || (perm & PTE_P) == 0 || (perm & PTE_U) == 0)
        return -E_INVAL;
    if((unsigned int)va >= UTOP || (unsigned int)va % PGSIZE != 0)
        return -E_INVAL;
    struct Env * env;
	if(envid2env(envid, &env, 1) < 0)
        return -E_BAD_ENV;
    struct Page * page;
    if(page_alloc(&page) != 0)
        return -E_NO_MEM;
    if(page_insert(env->env_pgdir, page, va, perm) < 0)
    {
        page_free(page);
        return -E_NO_MEM;
    }
    uint32_t cr3 = rcr3();
    lcr3(env->env_cr3);
    memset(va, 0, PGSIZE);
    lcr3(cr3);
    return 0;
    
	//panic("sys_page_alloc not implemented");
}

// Map the page of memory at 'srcva' in srcenvid's address space
// at 'dstva' in dstenvid's address space with permission 'perm'.
// Perm has the same restrictions as in sys_page_alloc, except
// that it also must not grant write access to a read-only
// page.
//
// Return 0 on success, < 0 on error.  Errors are:
//	-E_BAD_ENV if srcenvid and/or dstenvid doesn't currently exist,
//		or the caller doesn't have permission to change one of them.D
//	-E_INVAL if srcva >= UTOP or srcva is not page-aligned,
//		or dstva >= UTOP or dstva is not page-aligned.D
//	-E_INVAL is srcva is not mapped in srcenvid's address space.D
//	-E_INVAL if perm is inappropriate (see sys_page_alloc).D
//	-E_INVAL if (perm & PTE_W), but srcva is read-only in srcenvid's
//		address space.
//	-E_NO_MEM if there's no memory to allocate any necessary page tables.
static int
sys_page_map(envid_t srcenvid, void *srcva,
	     envid_t dstenvid, void *dstva, int perm)
{
	// Hint: This function is a wrapper around page_lookup() and
	//   page_insert() from kern/pmap.c.
	//   Again, most of the new code you write should be to check the
	//   parameters for correctness.
	//   Use the third argument to page_lookup() to
	//   check the current permissions on the page.

	// LAB 4: Your code here.
	if((unsigned int)srcva >= UTOP || (unsigned int)dstva >= UTOP || (unsigned int)srcva % PGSIZE != 0
       || (unsigned int)dstva % PGSIZE != 0)
        return -E_INVAL;
    if((perm | PTE_USER) != PTE_USER || (perm & PTE_P) == 0 || (perm & PTE_U) == 0)
        return -E_INVAL;
    struct Env *src, *dst;
    if(envid2env(srcenvid, &src, 1) || envid2env(dstenvid, &dst, 1))
        return -E_BAD_ENV;
    pte_t * store;
    struct Page * page = page_lookup(src->env_pgdir, srcva, &store);
    if(page == NULL)
        return -E_INVAL;
    if((perm & PTE_W) && ((*store | PTE_W) == 0))
        return -E_INVAL;
    if(page_insert(dst->env_pgdir, page, dstva, perm) != 0)
        return -E_NO_MEM;
    return 0;
    
	//panic("sys_page_map not implemented");
}

// Unmap the page of memory at 'va' in the address space of 'envid'.
// If no page is mapped, the function silently succeeds.
//
// Return 0 on success, < 0 on error.  Errors are:
//	-E_BAD_ENV if environment envid doesn't currently exist,
//		or the caller doesn't have permission to change envid.
//	-E_INVAL if va >= UTOP, or va is not page-aligned.
static int
sys_page_unmap(envid_t envid, void *va)
{
	// Hint: This function is a wrapper around page_remove().

	// LAB 4: Your code here.
	if((unsigned int)va >= UTOP || ((unsigned int)va % PGSIZE != 0))
        return -E_INVAL;
    struct Env * env;
    if(envid2env(envid, &env, 1) != 0)
        return -E_BAD_ENV;
    page_remove(env->env_pgdir, va);
    return 0;
	//panic("sys_page_unmap not implemented");
}

// Try to send 'value' to the target env 'envid'.
// If srcva < UTOP, then also send page currently mapped at 'srcva',
// so that receiver gets a duplicate mapping of the same page.
//
// The send fails with a return value of -E_IPC_NOT_RECV if the
// target is not blocked, waiting for an IPC.
//
// The send also can fail for the other reasons listed below.
//
// Otherwise, the send succeeds, and the target's ipc fields are
// updated as follows:
//    env_ipc_recving is set to 0 to block future sends;
//    env_ipc_from is set to the sending envid;
//    env_ipc_value is set to the 'value' parameter;
//    env_ipc_perm is set to 'perm' if a page was transferred, 0 otherwise.
// The target environment is marked runnable again, returning 0
// from the paused sys_ipc_recv system call.  (Hint: does the
// sys_ipc_recv function ever actually return?)
//
// If the sender wants to send a page but the receiver isn't asking for one,
// then no page mapping is transferred, but no error occurs.
// The ipc only happens when no errors occur.
//
// Returns 0 on success, < 0 on error.
// Errors are:
//	-E_BAD_ENV if environment envid doesn't currently exist.
//		(No need to check permissions.)
//	-E_IPC_NOT_RECV if envid is not currently blocked in sys_ipc_recv,
//		or another environment managed to send first.
//	-E_INVAL if srcva < UTOP but srcva is not page-aligned.
//	-E_INVAL if srcva < UTOP and perm is inappropriate
//		(see sys_page_alloc).
//	-E_INVAL if srcva < UTOP but srcva is not mapped in the caller's
//		address space.
//	-E_INVAL if (perm & PTE_W), but srcva is read-only in the
//		current environment's address space.
//	-E_NO_MEM if there's not enough memory to map srcva in envid's
//		address space.
static int
sys_ipc_try_send(envid_t envid, uint32_t value, void *srcva, unsigned perm)
{
	// LAB 4: Your code here.
	//panic("sys_ipc_try_send not implemented");
    struct Env *dstenv;
    curenv->env_ipc_sent = envid;
    if(envid2env(envid, &dstenv, 0) != 0)
        return -E_BAD_ENV;
    if(dstenv->env_ipc_recving == 0)
    {
        // cprintf("current id,%x\n", curenv->env_id);
         return -E_IPC_NOT_RECV;
        
        
        
    }
    // cprintf("out of \n");
    pte_t * addr;
    struct Page* page;
    if(curenv->env_sent_suc > dstenv->env_suc_min)
    {
       /* / curenv->env_fail_time ++; */
       /*  cprintf("DEBUG fail_time:%d,%x,%x\n", curenv->env_fail_time,dstenv->env_min_sent,curenv->env_id); */
       /*  struct Env * temp; */
       /*  envid2env(dstenv->env_min_sent, &temp, 0); */
       /*  if(curenv->env_fail_time > temp->env_fail_time) */
       /*  { */
        // cprintf("id change"); 
            
       /*      dstenv->env_min_sent = curenv->env_id; */
       /*  } */
        //cprintf("come on\n");
        // sys_yield();
        return -E_IPC_NOT_RECV;
        //return -E_BAD_ENV;
    }
    if((uint32_t)srcva < UTOP && (uint32_t)srcva != 0)
    {
        if((uint32_t)srcva % PGSIZE)
            return -E_INVAL;
        page = page_lookup(curenv->env_pgdir, srcva, &addr);
        if(page == NULL)
            return -E_INVAL;
        if(!((perm & PTE_U) && (perm & PTE_P)))
            return -E_INVAL;
        if((perm & PTE_W) && !(*addr & PTE_W))
            return -E_INVAL;
        if(page_insert(dstenv->env_pgdir, page, dstenv->env_ipc_dstva, perm) != 0)
            return -E_NO_MEM;
        else
            dstenv->env_ipc_perm = perm;
    }
    
    if((uint32_t)srcva >= UTOP)
        dstenv->env_ipc_perm = 0;

    

    dstenv->env_ipc_value = value;
    dstenv->env_ipc_from = curenv->env_id;
    dstenv->env_ipc_recving = 0;
    dstenv->env_status = ENV_RUNNABLE;
    curenv->env_sent_suc++;
    //curenv->env_ipc_sent = -1;
    dstenv->env_suc_min = 0x7fffffff;
    struct Env * evptr;
    for(evptr = envs; evptr < envs + NENV; evptr++)
    {
        if(evptr->env_ipc_sent == envid)
            if(evptr->env_sent_suc < dstenv->env_suc_min)
                dstenv->env_suc_min =evptr->env_sent_suc;
    }
    
    return 0;
        
    
}

// Block until a value is ready.  Record that you want to receive
// using the env_ipc_recving and env_ipc_dstva fields of struct Env,
// mark yourself not runnable, and then give up the CPU.
//
// If 'dstva' is < UTOP, then you are willing to receive a page of data.
// 'dstva' is the virtual address at which the sent page should be mapped.
//
// This function only returns on error, but the system call will eventually
// return 0 on success.
// Return < 0 on error.  Errors are:
//	-E_INVAL if dstva < UTOP but dstva is not page-aligned.
static int
sys_ipc_recv(void *dstva)
{
	// LAB 4: Your code here.
	//panic("sys_ipc_recv not implemented");
    curenv->env_ipc_recving = 1;

    //cprintf("rev,dstva:%x,eid,%x\n", dstva,curenv->env_id);
    
    if((uint32_t)dstva < UTOP)
    {
        if((uint32_t)dstva % PGSIZE)
            return -E_INVAL;
        curenv->env_ipc_dstva = dstva;
        
    }
    curenv->env_status = ENV_NOT_RUNNABLE;
    
	return 0;
}


// Dispatches to the correct kernel function, passing the arguments.
int32_t
syscall(uint32_t syscallno, uint32_t a1, uint32_t a2, uint32_t a3, uint32_t a4, uint32_t a5)
{
	// Call the function corresponding to the 'syscallno' parameter.
	// Return any appropriate return value.
	// LAB 3: Your code here.
    switch(syscallno)
    {
        case SYS_cputs:
            sys_cputs((const char*)a1, (size_t)a2);
            return 0;
        case SYS_env_destroy:
            return sys_env_destroy(a1);
        case SYS_getenvid:
            return sys_getenvid();
        case SYS_yield:
            sys_yield();
            return 0;
        case SYS_page_alloc:
            return sys_page_alloc((envid_t)a1, (void *)a2, (int)a3);
        case SYS_page_map:
            return sys_page_map((envid_t)a1, (void *)a2, (envid_t)a3, (void *)a4, (int)a5);
        case SYS_page_unmap:
            return sys_page_unmap((envid_t)a1, (void *)a2);
        case SYS_exofork:
            return sys_exofork();
        case SYS_env_set_status:
            return sys_env_set_status((envid_t)a1, (int)a2);
        case SYS_env_set_pgfault_upcall:
            return sys_env_set_pgfault_upcall((envid_t)a1, (void *)a2);
        case SYS_ipc_recv:
            return sys_ipc_recv((void *)a1);
        case SYS_ipc_try_send:
            return sys_ipc_try_send(a1, a2, (void *)a3, a4);
        case SYS_env_set_trapframe:
            return sys_env_set_trapframe(a1,(struct Trapframe*)a2);
        default:
            return -E_INVAL;
    }
    
    
    //    panic("syscall not legal");
    return -E_INVAL;
}

